Disposable diapers have met with increased commercial acceptance in recent years primarily because of their convenience, as opposed to cloth diapers, which need to be laundered once soiled. Many different constructions have been proposed and used, and some have met with widespread commercial success in spite of certain inadequacies in functional properties.
One of the most serious prior art problems has been the inability to provide a suitable construction that would keep moisture away from the surface of the diaper which comes into contact with the infant's skin and thereby avoids skin irritation and infection. Commonly assigned Mesek et al U.S. Pat. No. 3,612,055 discloses several diaper constructions that function very well in keeping moisture away from an infant's skin, while at the same time handling a full volume discharge of urine.
These functions are accomplished by a multilayer diaper comprising, in order, a fibrous facing layer which is to be brought into contact with the infant's skin, a layer of a highly porous, loosely compacted cellulosic batt, a paper-like densified, highly compacted cellulosic fibrous layer integral with the loosely compacted batt, and a moisture-impervious backing sheet adhered to the densified layer at the interface therebetween. The facing layer is of porous construction and its fibers have less wettability for water than the fibers of the loosely compacted batt, resulting in a tendency for liquid to flow from the facing layer into the batt. The densified fibrous layer has a smaller average pore size than the loosely compacted batt, resulting in a tendency for liquid to flow preferentially from the batt into the underlying densified layer rather than to other areas of the batt, thus tending to restrict wetting in the batt to an area of moderate size. Liquid flowing into the densified layer tends to spread laterally because of its wicking action and liquid which might pass through the densified layer during discharge (when flow is rapid) is held back by the impervious backing sheet for sufficient time to permit absorption to take place. Liquid in excess of the absorptive capacity of the densified layer is forced back by the impervious layer into the dry portion of the loosely compacted batt, thus utilizing the additional absorptive capacity therein.
While the diaper structure described in the abovementioned patent represents a significant advance in the art, particularly in its ability to maintain the layer in contact with an infant's skin dry, during periods of heavy discharge, after the densified layer and integral loosely compacted batt becomes saturated, there is a tendency for urine to wick back into the facing layer.
Also there exists a need for a disposable training panty which can be used during the transition period between diapers and reusable undergarments. An undergarment of this general type would also be useful with incontinent adults and children because of their absorbent properties, fit, and disposability.
Currently available training pants are generally made from knitted or woven cloth, such as cotton, or cotton-polyester blends. They may or may not include additional absorbent layers in the crotch area and they may include a water-repellent outer layer.
The prior art and commercially available training pants suffer from a number of disadvantages, however. Aside from the obvious disadvantage of having to be laundered, the primary disadvantage of the currently available conventional cloth training panty is the problem of liquid strike-through. The prior art has attempted to solve this problem by providing areas of extra absorbency utilizing, for example, terrycloth or a piled fabric in the crotch portion of the panty and/or additionally including a water-repellent outer layer in the crotch area, or over the entire outer surface of the panty. However, as anyone knows who has ventured through the traumatic training period with their babies, the prior art simply has not provided a satisfactory solution.
For the above reasons, many mothers continue to use diapers during the training period, rather than suffer the annoyance of liquid strike-through when their child has an accident. While the use of diapers substantially reduces the problem of liquid strike-through diaper use during the training period is highly undesirable and tends to prolong the period required to completely train the child. Psychologically, it is desirable for children to be in panties during the training period so they are aware of no longer being babies and are more aware of accidents.
Aside from the undesirable psychological drawbacks of continuing to use diapers during the training period, disposable diapers present an economic drawback. Disposable diapers generally utilize tape tab fasteners in place of safety pins as fastening means. When the tabs are removed so that the child can be placed on the toilet, the unsoiled diaper must be discarded because the currently available tabs are for a single use only and usually tear the backing fabric when they are pulled away.
A variety of disposable panties are known. See, for example, U.S. Pat. Nos. 3,424,162; 3,599,638; 3,599,640; and 3,636,953. Such panties are provided with or adapted to receive a sanitary napkin in the crotch portion of the panty and are not adapted to deal with the liquid strike-through problem encountered during the training period or with incontinent adults or children. Similarly, the disposable panty types disclosed in U.S. Pat. Nos. 3,663,962; 3,245,407 and 3,488,778, do not satisfy the need for a disposable training panty, because the panties are either nonabsorbent, such as plastic, or lack the necessary fit in the leg and waist area to prevent the problem of liquid strike-through and leakage.
In accordance with co-pending application U.S. Ser. No. 898,374, filed Apr. 20, 1978, a disposable undergarment is provided which is used as a training panty during the training period. The undergarment is constructed of one or more plies of stretchable non-woven fabric. Preferably, several plies of stretchable, non-woven fabric are utilized to provide different absorption and moisture-permeability characteristics for the inner and the outer layer of the undergarment, as well as good conformability and fit without attendant bulkiness. The inner, or facing, layer of the undergarment provides an innermost ply having a soft surface for contact with the wearer's skin, readily permits passage of excreted body liquids therethrough, and can provide an absorbent mass for body liquids as well, if desired. The outer, or backing, layer of the undergarment, on the other hand, presents at least one ply which is an effective liquid barrier and which prevents or substantially minimizes body liquid strike-through. The non-woven outer fabric layer, as well as the non-woven inner fabric layer, are micropleated in the machine direction of the fabric and compacted in the cross-direction of the fabric to give enhanced stretch or extensibility characteristics.
A preferred disposable undergarment comprises two stretchable, non-woven fabric layers having one or more plies each, preferably compressively-shrunk non-woven fabrics, and an absorbent layer or panel which is disposed between the inner and outer layers at least in the crotch portion of the undergarment. If desired, the absorbent layer can extend further up the back and/or the front portions of the undergarment. The undergarment has a self-fitting waist aperture and self-fitting leg apertures.
Further description of the training panty appears in the aforementioned co-pending application which is incorporated herewith by reference.
The absorbent structure disclosed herein represents an improvement over the absorbent structures disclosed in the above-mentioned patent and co-pending application by providing a liquid barrier between the absorbent batt and the infant's skin to prevent the urine from flowing back and wetting the infant's skin.